In the past, it has been known to provide connections to contact pads formed along the edges of a circuit card, particularly a thin-film or thick-film circuit having a rigid substrate, using an edge connector in the form of a spring clip having at least three resilient fingers or tines for engaging and holding portions of the card. In a typical example, as disclosed in J. Seilder U.S. Pat. No. 4,120,558 (herein incorporated by reference), the three tines are arranged in a row, with the center tine offset from the outer two tines so that the edge of the circuit card may be inserted between the three tines to pre-assemble the card with the clip, and with the card being held in place by spring action of the tines engaging portions of the card. With this arrangement, the center tine is positioned adjacent to the contact pad, and carries a solder preform, such as a cylindrical slug of solder, which is subsequently melted so as to bond the clip to the pad area and to connect the pad electrically to the clip for external contact purposes.
In such a prior construction, as typified by the Seilder patent, the solder preform is carried by the center tine a fixed distance above the substrate surface and pad area to be bonded, for example 0.010 inches (0.25 mm) in a typical prior-art example. This spacing or gap between preform and substrate has led to problems in initiating solder flow to the substrate and in obtaining a good solder joint, as discussed in further detail toward the end of the following "Detailed Description."